Reversible tooth with snap-on holding means



Dec. 20, 1966 A. PETERSEN 3,292,231

I REVERSIBLE TOOTH WITH SNAP-ON HOLDING MEANS Filed Jan. 17. 1964 INVENTOR. GERALD A. PETERSEN.

ATTORNEY United States Patent SNAP-9N This invention relates to a new and improved replaceable tooth for earth-digging equipment. More particularly, the invention relates, in part, to an improvement in that type tooth and tooth-holder wherein the tooth is formed with prongs at its proximal end and the toothholder is formed wih a web generally but not precisely complementary to the shape of the slot. The web fitting in the slot provides stability for the tooth.

The invention further relates to a tooth having prongs provided with protuberances and a forward extension in the slot defining the prongs. A feature of the invention is the fact that the prongs are slightly flexible and are provided with outwardly disposed projections which fit into depressions in the tooth-holder to hold the tooth in place in a snap-on fashion.

Earth-digging equipment, such as angers and trenchers, is commonly provided with teeth along the working edges disposed at angles with respect to the direction of movement of the equipment relative to the ground. Such teeth wear with the passage of time and it is necessary to remove and replace the same. The present invention provides a convenient means for retaining the tooth in its holder in such fashion that the tooth can be driven out of the holder and replaced.

The present invention provides an improved means for holding a tooth in its holder or shank in such manner that it can be installed and replaced with a minimum of labor.

A feature of the present invention is the fact that independent means such as keys, bolts and various other retaining members are not required in that the shape of the tooth and its holder, plus the fact that the prongs may be spread apart or together and spring back to initial position, makes it possible to hold the tooth securely in place without such independent means.

Other objects of the present invention will become apparent'upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIG. 1 is an exploded perspective view partly broken way in section showing the tooth and its holder in accordance with one form of the invention.

FIG. 2 is a horizontal sectional view taken substantially along the lines 22 of FIG. 1.

FIG. 2A is a fragmentary sectional view similar to FIG. 2 of a modification.

FIG. 3 is a view similar to FIG. 2 of another modified form of tooth and holder.

FIG. 4 is a transverse sectional view taken substantially along the line 44 of FIG. 3.

The tooth 11 of the present invention is intended for installation in earth angers, trenching machines and similar earth-digging equipment. Such equipment has either integral therewith or bolted or otherwise fastened thereon a tooth-holder 12 to receive one or more removable teeth 11. The number of teeth, their spacing, and the angular position thereof with relation to the tooth-holder are subjec to considerable variation.

In the form of the invention shown in FIG. 1, the toothholder 12 is illustrated to receive single tooth 11, but it will be understood that the tooth-holding means may be duplicated as reqiured. Tooth-holder 12 is formed with 3,292,281 Patented Dec. 20, 1966 "ice cavities 13 facing forward and defined by top and bottom walls 14, 16, having opposed top and bottom surfaces 17, 18, respectively, which are generally parallel to each other and also having interconnecting side edge walls 19. Extending between the top and bottom walls 14, 16 approximately midway between edge walls 19 is web 21. Accordingly, cavities 13 are similar and separated from each other by web 21. In order to force tooth 11 from its holder, openings 22 are formed in the back of the toothholder to provide access to the back of each cavity 13 and the proximal end of the tooth 11 held therein.

As viewed in horizontal section (FIG. 2), web 21 has a narrow, substantially rectangular forward projection 23 of lesser width than the main portion of the web to provide lateral stability to the tooth in the event that the corner of the tooth hits a hard object at an angle. Projection 23 terminates in a transverse vertical end 25. Rearwardly of the forward projection 23, the web widens out to either side to provide a shoulder 24 which bears the principal thrust of the tooth when it is digging. Rearwardly of the shoulder, the web tapers rearwardly in walls 26 to a narrow portion 27 of lesser width to provide clearance for inward movement of the tooth prongs as hereinafter described, and rearward of slanted walls 26 the narrow web portion 27 extends to the back of cavities 13.

Inner surfaces 30 of side edge walls 19 are substantially straight and parallel at the rear of cavities 13. Outward concave sockets 31 are formed in each side edge wall 19 spaced rearwardly of the front edge of holder 12 a predetermined distance for a purpose hereinafter explained. Forward of socket 31, the walls 32 of edges 19 taper outward.

The tooth 11 used with the holder of FIGS. 1 and 2, is formed of a unitary piece of hard material and has a distal portion which is substantially rectangular in plan having forwardly converging top and bottom faces 32, 33 commencing about at transverse line 40 terminating in a blunt transverse cutting edge 34, extending transversely across the tooth. The side edges 35 are parallel and straight and spaced apart a greater distance than side edges 35 of holder 12 so that the tooth absorbs the edge wear of the digging action.

The proximal end of tooth 11 is divided into prongs 37 by medial slot 38 extending forward from the proximal end. The shape of slot 38 is subject to a certain amount of variation. However, at its forward end extension 39 is considerably narrower than the main portion of slot 33 at the rearward end and has vertical parallel walls 41 which are spaced apart a distance slightly greater than the thickness of the forward extension 23 of web 21. Forward end 42 of extension 39 is transverse and vertical and is positioned to fit against the forward end 25 of web 21. At the rearward end of narrow portion 39, the slot widens out in outward transverse vertical shoulders 43 which fit snugly against the shoulders 24 of web 21 and cooperate to transmit the principal thrust from tooth 11 to holder 12 during digging. To either side of shoulder 43 the slot 38 extends in substantially parallel vertical inner edges 44 which are spaced apart a distance greater than the maximum thickness of web 21. The ends 46 of prongs 37 are transverse and vertical. The outer edges 48 of prongs 37 are vertical and extend straight back spaced apart a distance substantially less than that between side edges 36 and about in line with walls 30. Thus tooth 11 is divided by slot 38 into two prongs 37, each substantially rectangular in cross-section and each in plan of irregular shape. The top and bottom surfaces of prongs 37 are substantially parallel and spaced apart the distance between surfaces 17, 18. The outside edge 48 of each prong adjacent the proximal end is formed with an outward protuberance 47. Slanted surfaces 49 are formed rearward of protuberances 47. Protuberances 47 are so located as to fit into sockets 31 in wall 19 of toothholder 12 when the tooth is in place in the holder.

Tooth 11 is formed at its distal end of a hard material which resists the wear of the digging action. However, prongs 37 are sufliciently resilient or flexible so that the prongs will bend inwardly when the prongs are forced into the cavities 13 in the holder and the protuberances 47, and particularly. slanted surfaces 49 ride on the tapered edge walls until protuberances 47 encounter sockets 31' whereupon the resiliency of the prongs forces the protuberances outwardly and the tooth snaps into place.

When it is necessary to replace the tooth, a tool (not shown) may be inserted through the opening 22 in the back of cavity 13 or through optional openings 50 in the side edges 19 to force prongs 37 inwardly toward each other and permit the tooth to be driven or pulled out of its holder. Alternatively, as shown in the upper half of FIG. 2, an oblique opening 51 in edge 19 may be formed for purpose similar to opening 22.

A feature and advantage of the invention is the use of the forward extension 23 of web 21 fitting into the corresponding narrow portion 39 of slot 38 which provides stability for the tooth and keeps the tooth from twisting out of alignment when it encounters a sharp object, such as a rock hitting against a corner of the distal cutting edge 34.

The form of the invention shown in FIG. 2A is similar to that shown in FIGS. 1 and 2, and corresponding identical parts are marked with the same reference numerals. However, side edges 19a do not extend fully forward to the front end of holder 12a, as in the preceding modification and hence slanted walls 32 are eliminated. Instead, the edge walls 19a terminate in rounded ends 51 slightly ahead of sockets 31. When proturberances 47 encounterv ends 51 as the prongs 37 are forced into cavities 13a, prongs 37 bend inward until protuberances 47 snap into sockets 31. Because of the accessibility of sockets 31 from the front of the holder, openings 22 or 49 are not essential and are eliminated. Web 21 is formed so that its rearward portion 27a curves around to merge with edges 19a, as indicated by reference numeral 52.

In the form of the invention shown in FIGS. 3 and 4, the protuberances 47b are formed on the inside wall edges 44b of each prong 37 rather than on the outside thereof. Further, transverse shoulders 56 are formed interconnecting extension side walls 41 and slanted shoulders 43b. In other respects, the shape of the tooth is similar to the shape shown in FIGS. 1, 2 and 2A, and similar reference numerals are used. Web 21b also is somewhat similar in shape, except that side edges 19 (or 19a) are eliminated and sockets'31 are formed in the side walls 44b of the Web spaced backward from the front end of holder 12b a suflicient distance so that protuberances 47b mate in said sockets. Because protuberances 47b are formed on the inside wall 44b of the prong rather than the outside, the side edges 19 as shown in FIGS. 1 and 2 are not necessary, although their presence is optional. Transverse web shoulders 58 receive the thrust of prong shoulders 56 and slanted walls 24b fit tightly against slanted slot walls 43b.

In the form of the invention shown in FIGS. 3 and 4, tooth 11b is driven backward into openings between the top and bottom portions 14b, 16b and prongs 37 spread apart sufliciently to allow the protuberances 47b to clear the side walls 44b of web 27b. The prongs 37 snap together and protuberances 47b fit into sockets 31b to hold the tooth in place.

Openings 22b are formed behind tooth proximal ends 46 communicating With the rear end thereof to enable an instrument to be inserted to pry the protuberances 47b out of their sockets 31b and force tooth 11b forwardly out of holder 12b.

Although the foregoing invention has been described in some detail, by way of illustration and example for and formed with a substantially medial slot extending forward from the proximal end of the tooth extending between said top and bottom surfaces and dividing said proximal'end into two prongseach substantially rectangular in cross-section, each said prong formed with a protuberance along one side edge adjacent the proximal end of said tooth, said prongs being resiliently flexible in directions toward and away from said slot, said protuberances moving toward and away from each other upon flexing of said prongs said tooth having its distal portion projecting out of said tooth-holder and said prongs in said tooth-holder, said tooth-holder comprising top and bottom Walls engaging said top and bottom surfaces of said proximal portion of said tooth, a web interconnecting said top and bottom walls and traversing said slot, said web having a forward extension fitting into said forward extension of said slot, said tooth-holder having substantially vertical Walls formed with sockets to receive said protuberances on said prongs, said walls slanted forwardly of said sockets to engage said protuberances as said tooth is driven into said tooth-holder and to bend said prongs by said slanted surfaces wedging said protubernaces relative to each other, whereby said prongs bend and then return to original position relative to each other with said protuberances fitting in said sockets to restrain unintentional withdrawal of said tooth from said tooth-holder and said ex tension of said web filling said extension of said slot.

2. In the combination of claim 1 in which said distal portion in plan being substantially rectangular and in which the top and bottom surfaces converge forwardly, the side edges of said distal portion being substantially wider than the outside side edges of said prongs.

3. The combination of claim 1, in which said protuberances are formed on the outside side edges of said prongs, said tooth-holder formed with side edge walls generally parallel to said web, said sockets formed in said side edge walls, said side edge walls slanted outwardly forwardly of said sockets.

4. The combination of claim 3, in which said sideedge walls extend forwarly approximately even with the forward end of said web.

5. The combination of claim 3, in which said side edge, 1

walls terminate slightly forwardly of said sockets.

6. The combination of claim 1, in which said protruberances are formed on the inside side edges of said prongs, said web walls formed with said sockets.

7. The combination of claim 1, in which said tooth is 1 formed with slot shoulders outwardly rearwardly of the rearward end of said forward extension of said slot, said tooth-holder having web shoulders abutting said slot shoulders when said tooth is in place with said protuberances in said sockets.

References Cited by the Examiner UNITED STATES PATENTS ABRAHAM G. STONE, Primary Examiner. WILLIAM A. SMITH IH, Examiner. 

1. IN COMBINATION, A TOOTH AND A TOOTH-HOLDER, SAID TOOTH COMPRISING A UNITARY PIECE OF HARD MATERIAL HAVING A DISTAL PORTION FORMED WITH A CUTTING EDGE AND A PROXIMAL PORTION, SAID PROXIMAL PORTION HAVING TOP AND BOTTOM SURFACES AND FORMED WITH A SUBSTANTIALLY MEDIAL SLOT EXTENDING FORWARD FROM THE PROXIMAL END OF THE TOOTH EXTENDING BETWEEN SAID TOP AND BOTTOM SURFACES AND DIVIDING SAID PROXIMAL END INTO TWO PRONGS EACH SUBSTANTIALLY RECTANGULAR IN CROSS-SECTION, EACH SAID PRONG FORMED WITH A PROTUBERANCE ALONG ONE SIDE EDGE ADJACENT THE PROXIMAL END OF SAID TOOTH, SAID PRONGS BEING RESILIENTLY FLEXIBLE IN DIRECTIONS TOWARD AND AWAY FROM SAID SLOT, SAID PROTUBERANCES MOVING TOWARD AND AWAY FROM EACH OTHER UPON FLEXING OF SAID PRONGS SAID TOOTH HAVING ITS DISTAL PORTION PROJECTING OUT OF SAID TOOTH-HOLDER AND SAID PRONGS IN SAID TOOTH-HOLDER, SAID TOOTH-HOLDER COMPRISING TOP AND BOTTOM WALLS ENGAGING SAID TOP AND BOTTOM SURFACES OF SAID PROXIMAL PORTION OF SAID TOOTH, A WEB INTERCONNECTING SAID TOP AND BOTTOM WALLS AND TRAVERSING SAID SLOT, SAID WEB HAVING A FORWARD EXTENSION FITTING INTO SAID FORWARD EXTENSION OF SAID SLOT, SAID TOOTH-HOLDER HAVING SUBSTANTIALLY VERTICAL WALLS FORMED WITH SOCKETS TO RECEIVE SAID PROTUBERANCES ON SAID PRONGS, SAID WALLS SLANTED FORWARDLY OF SAID SOCKETS TO ENGAGE SAID PROTUBERANCES AS SAID TOOTH IS DRIVEN INTO SAID TOOTH-HOLDER AND TO BEND SAID PRONGS BY SAID SLANTED SURFACES WEDGING SAID PROTUBERNACES RELATIVE TO EACH OTHER, WHEREBY SAID PRONGS BEND AND THEN RETURN TO ORIGINAL POSITION RELATIVE TO EACH OTHER WITH SAID PROTUBERANCES FITTING IN SAID SOCKETS TO RESTRAIN UNINTENTIONAL WITHDRAWAL OF SAID TOOTH FROM SAID TOOTH-HOLDER AND SAID EXTENSION OF SAID WEB FILLING SAID EXTENSION OF SAID SLOT. 